Note: This adaptor can also fit a bigger microscope eyepiece tube by putting some soft materials (eg. tapes or rubber bands) around its cone shaped barrel. The major advantage of this cone shaped adaptor is that it can fit eyepiece tubes with diameters from 22mm to 24mm or larger. But this adaptor is not as stable as a similar 1.25" adapter with straight barrel shape. So if you wish to attach a heavy DSLR camera to microscopes for digiscoping, for example, you should consider the other adapter.